This invention relates to current limiting fuses for use in electrical power distribution systems and particularly to chemically augmented fuses.
Electrical fuses provide a relatively inexpensive means of current interruption in a large variety of applications. For example, fuses can be utilized in multi-phase electrical power distribution systems to interrupt current on the occurrence of a fault. Interruption of current protects the transmission lines as well as the equipment connected thereto.
It is desired that current interruption devices operate for a variety of abnormal conditions, such as, for example, hot oil in a transformer, high pressure inside a transformer tank, or the failure of a secondary protective device such as a circuit breaker or other fuse. In multi-phase electrical power transmission systems, it is desirable that current is interrupted in all three phases upon the occurrence of a fault in a single one of the phases. This prevents "single phasing" of connected equipment and the associated risk of damage. It is also desirable that an external signal, derived for example from a secondary protection relay scheme, be capable of causing a fuse to operate and interrupt a circuit containing one or more fuses independent of the current flowing through the fuses.